The invention relates to a module for treating fluids with one or more cells stacked one on top of the other, each of these having at least one opening, the opening of the cell or the similar openings of the cells together forming at least one channel for feeding the fluid to be treated, each cell having two flat, porous components delimiting an inner space, and the inner space or spaces being connected to the channel. The invention also relates to a method for manufacturing such modules.
In filtration technology it is known to use filter candles with fillings which either form a precoat or are introduced in the dry state.
Such a filter device is known from DE 39 43 249 A1. This comprises a perforated core pipe, a perforated support casing, a completely closed top closure cap carrying a guide element, and a bottom closure cap having a central opening with a connection piece connected thereto. The cavity formed between the core pipe, the support casing and the two closure caps is filled with bulk material consisting of reclaimable filtration-active substances. The fluid to be filtered flows in radial direction from the outside to the inside, and the filtrate is discharged through the core pipe.
The disadvantage of this device is that it must be filled by the candle manufacturer because the filled cavity is closed when the top closure cap is fitted. This means that the user must specify the type of filling material when ordering the filter candle. A further disadvantage is that the filling may settle when transported or stored for a longer time, thereby creating a free space through which the unfiltered fluid flows through the candle.
DE 38 02 816 A1 describes a candle-shaped filter element, the outer circumferential wall of which is in the form of a porous support layer for a filter cake. This filter cake is formed by precoating filter material, for example, kieselguhr or fiber mixtures and adsorbents such as activated carbon, silicic acid material and the like. When the filter cake is worn out, it is washed away by back flushing and replaced by a new precoated filter cake, and the precoated filter material of the removed filter cake has to be recovered in a complicated way outside the filter housing. It is, at any rate, necessary to precoat a new filter cake prior to continuing with the filtering operation. This filtering device has the disadvantage that only precoatable materials can be used.
DE 32 04 022 C2 describes a filter cartridge which is supposed to have greater stability and improved efficiency. The cartridge has a coaxial structure and is filled with filtration-active material through which the fluid flows essentially in axial direction owing to the walls being formed by permeable and impermeable sections.
In filtration technology it is also known to use filter modules having a number of filter cells which are stacked one on top of the other and each have a central opening.
These filter modules differ in their design and operation.
A variant of these known filter modules has a central support pipe on which the prefabricated filter cells are arranged in a row between two adapters attached at the ends. When assembling the filter module, the filter cells are pressed together and held so as to be sealed from one another. Such a filter module is described, for example, in DE 37 41 552 A1, where prefabricated filter cells are used.
Another variant of known filter modules dispenses with a support pipe. On their inner circumference the filter cells are provided at the central opening with retaining and connecting rings which are welded together when stacking the filter cells on one another so as to join the filter module and make it into a solid unit. Other embodiments provide spacer and/or drainage elements which are arranged as disc-shaped elements between the filter layers and/or filter cells and make it possible for these to be mechanically joined to one another.
In spite of different designs of the filter modules, the filter cells have in common that the filter sheets are made of flat materials such as, for example, filter cardboards, papers, tiles or fabrics.
So-called filter layers are widely used as filter sheets. A depth-filter material comprising organic and/or inorganic fibrous and/or granular substances is to be understood by this term.
As a rule, cellulose and/or plastic fibers which may have filtration-active substances such as, for example, kieselguhr or pearlites embedded therein are used as base material for these filter layers. Kieselguhr and pearlites serve to enlarge the inner surface and therefore increase the capacity to absorb the turbid matter.
The filter layers are used in fields ranging from clarification and treatment of liquids throughout the entire beverage industry to the pharmaceutical and chemical industries. Filter layers do not only have a screening effect whereby coarse particles are retained on the surface of the filter layer, but also, in particular, a depth effect for fine particles which are retained in the void spaces within the depth-filter material. Depending on the type of materials used, these filter layers may, for example, also have an adsorbing effect or interact with the unfiltered fluid in another way which goes beyond the purely mechanical filtration effect. Moreover, the surface may be subsequently treated for certain applications so as to prevent detachment of fibrous particles in the dry and damp states.
To date, the purpose of the filtration has always determined the composition of the filter layers. This means that production of the filter layers has always had to be preceded by definition of their subsequent range of application.
Since any conversion of the method of producing the filter layers entails problems and minimum quantities always have to be produced, small batches of specially adapted filter layers are relatively expensive.
The filter modules may be operated in two ways.
A filter module in which filter cells and support bodies are alternately stacked on one another along a central pipe is known from EP 0 233 999 A2. The filter cells also contain supporting structures for supporting the filter material of the filter cells. The unfiltered fluid is fed to the filter cells from the exterior, and the filtrate is discharged through the interior of the filter cells and through the central pipe. Herein it is disadvantageous that, on the one hand, the support bodies prevent uniform feed of the unfiltered fluid to the filter cells, and, on the other hand, the filter substances accumulate on the support bodies between the filter cells throughout the entire interior of the module filter.
To remedy these deficiencies it was proposed in DE 198 57 751.6-27 that the unfiltered fluid be fed through the central channel of the filter cells. These filter cells to which the fluid is fed from the interior require corresponding support bodies between the filter cells to prevent inflation of the filter layers during filtration. Filter modules designed and operated in this way are also referred to as inverse modules.
The object of the invention is to create a module which the user can individually adapt to the respective task in the treatment of fluids using housings and connections of existing filtration devices without any modification.
The object is accomplished by the interior of the cell or cells at least partially containing treatment material.